WO2022185593A1

WO2022185593A1 - Sound wave generation device

Info

Publication number: WO2022185593A1
Application number: PCT/JP2021/037862
Authority: WO
Inventors: 晋一佐々木; 隆昭浅田
Original assignee: 株式会社村田製作所
Priority date: 2021-03-03
Filing date: 2021-10-13
Publication date: 2022-09-09
Also published as: DE112021007200T5; US20230338989A1; JPWO2022185593A1; CN116762363A

Abstract

This sound wave generation device (10) comprises a drive circuit (12) and a power auxiliary circuit (13). The drive circuit (12) has: a capacitor (C1) charged by a DC power source (V1); and a drive switching element (T1) that supplies power from the capacitor (C1) to a sound wave source (11) that generates heat by being powered, and generates sound waves. The power auxiliary circuit (13) supplies power to the drive circuit (12) so that the power supplied to the sound wave source (1) is not reduced due to switching of the drive switching element (T1) during an operation for generating a series of sound waves from the sound wave source.

Description

sound wave generator

The present disclosure generally relates to sound wave generators. More specifically, the present disclosure relates to a sound wave generator that supplies power from a capacitor to a sound wave source that generates heat and generates sound waves when energized.

Patent Document 1 discloses a sound wave generator. The sound wave generator of Patent Document 1 includes a sound wave source, a switching element, a capacitor, and a limiting resistor. The sound wave source generates heat by current supplied from the DC power supply and generates sound waves. A limiting resistor is inserted between the DC power supply and the acoustic wave source to limit the current flowing from the DC power supply to the acoustic wave source. The switching element is connected in series with the acoustic wave source and is turned on/off to control the inflow/interruption of current flowing through the acoustic wave source. A capacitor is connected in parallel with the series circuit of the sound wave source and the switching element.

WO2019/159395

The present disclosure provides a sound wave generation circuit capable of stabilizing the sound pressure of a series of sound waves.

One aspect of the present disclosure is a sound wave generator that includes a drive circuit and a power auxiliary circuit. The drive circuit has a capacitor charged by a DC power supply, and a drive switching element that supplies power from the capacitor to a sound wave source that generates heat and generates sound waves when energized. The power auxiliary circuit provides power to the drive circuit such that switching of the drive switching element does not reduce the power provided to the source in the operation of generating a series of acoustic waves from the source.

One aspect of the present disclosure is a sound wave generator that includes a drive circuit and a power auxiliary circuit. The drive circuit has a capacitor charged by a DC power supply, and a drive switching element that supplies power from the capacitor to a sound wave source that generates heat and generates sound waves when energized. The power auxiliary circuit has an inductor electrically connected between the DC power supply and the capacitor, and a charging switching element electrically connected in parallel with the series circuit of the inductor and the DC power supply. The power auxiliary circuit supplies power to the drive circuit during off periods of the drive switching element in operation to generate a series of acoustic waves from the source by switching the drive switching element.

The aspect of the present disclosure can stabilize the sound pressure of a series of sound waves.

1 is a block diagram of a configuration example of an object detection system including a sound wave generator according to a first embodiment; FIG. A circuit diagram of a configuration example of the sound wave generator in FIG. Timing chart for explaining the operation of the sound wave generator of FIG. Graph of simulated voltage decay rate against capacitance of capacitor Graph showing measurement results of sound pressure of a series of sound waves output from the sound wave generator of FIG. Graph showing measurement results of sound pressure of a series of sound waves output from the sound wave generator of the comparative example Block diagram of a configuration example of an object detection system provided with a sound wave generator according to a second embodiment A circuit diagram of a configuration example of the sound wave generator in FIG. Timing diagram for explaining the operation of the sound wave generator of FIG. Block diagram of a configuration example of an object detection system provided with a sound wave generator according to a third embodiment A circuit diagram of a configuration example of the sound wave generator of FIG. Waveform diagram for explaining the operation of the sound wave generator of FIG. Waveform diagram for explaining the operation of the sound wave generator of the modified example

(Embodiment)
[1. Embodiment 1]
[1-1. Overview]
FIG. 1 is a block diagram of a configuration example of an object detection system 1 including a sound wave generator 10 according to a first embodiment. The object detection system 1 can detect an object in the target space using the sound wave P1. The object detection system 1 is used, for example, to detect an object such as an obstacle in a mobile object. Examples of mobile objects include vehicles such as automobiles, unmanned aircraft such as drones, and autonomous mobile robots. Autonomous mobile robots include robot cleaners.

As shown in FIG. 1, the sound wave generator 10 generates sound waves P1. The sound wave P1 is used in the object detection system 1 to detect an object and measure the distance to the object. The sound wave generator 10 includes a sound wave source 11 , a drive circuit 12 and a power auxiliary circuit 13 .

FIG. 2 is a circuit diagram of a configuration example of the sound wave generator 10. As shown in FIG. As shown in FIG. 2, the driving circuit 12 includes a capacitor C1 charged by a DC power source V1, and a driving switching element T1 that supplies power from the capacitor C1 to the sound wave source 11 that generates sound waves by generating heat when energized. have. The power auxiliary circuit 13 is designed so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. to power the

Since the sound wave generator 10 of FIG. 1 includes the power auxiliary circuit 13, sufficient electric power is supplied to the sound wave source 11 even in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. supply becomes possible. This makes it possible to suppress, or possibly prevent, a decrease in the sound pressure of the sound waves due to a decrease in the power supplied to the sound wave source 11 . As a result, a series of sound waves P1 can be output from the sound wave source 11 while suppressing a drop in sound pressure. As described above, according to the sound wave generator 10, the sound pressure of a series of sound waves P1 can be stabilized. For example, it is possible to output a series of sound waves P1 with the same sound pressure.

[1-2. detail]
The sound wave generator 10 and the object detection system 1 will be described below with reference to the drawings. As shown in FIG. 1 , the object detection system 1 includes a sound wave generator 10 , a wave receiver 20 and a processing circuit 30 .

[1-2-1. Sound wave generator]
The sound wave generator 10 of FIG. 1 includes a sound wave source 11, a drive circuit 12, a power auxiliary circuit 13, and a control circuit .

The sound wave source 11 generates heat when energized and generates sound waves P1. More specifically, the sound wave source 11 is a thermally excited element that heats air to generate sound waves P1. The sound wave source 11 is a so-called thermophone. The sound wave source 11 includes, for example, a heating element, a substrate, a pair of electrodes, and a heat insulating layer. A heating element is a resistor that generates heat when an electric current is passed through it. The heating element, for example, is arranged on the substrate so as to be in contact with the air. The air around the heating element expands or contracts due to the temperature change of the heating element. This generates air pressure waves or sound waves. The heat insulating layer suppresses heat conduction from the heating element to the substrate. The pair of electrodes are electrodes for applying current to the heating element from the outside of the sound wave source 11 . A pair of electrodes are provided on both sides of the heating element. Since the sound wave source 11 may have a conventionally well-known configuration, detailed description of the sound wave source 11 is omitted.

As shown in FIG. 2, the sound wave source 11 is electrically connected between the DC power supply V1 and ground.

The DC power supply V1 is composed of various power supply circuits and/or batteries. Various power supply circuits include, for example, AC/DC converters, DC/DC converters, regulators, and batteries. A voltage value of the DC power supply V1 is, for example, 5V.

The drive circuit 12 supplies power to the sound wave source 11 so that the sound wave source 11 generates the sound wave P1. The drive circuit 12, as shown in FIG. 2, includes a capacitor C1, a drive switching element T1, and a resistor R1.

The capacitor C1 is used to power the sound wave source 11. The capacitor C1 is electrically connected between the connection point between the DC power source V1 and the acoustic wave source 11 and the ground. Capacitor C1 is charged by DC power supply V1. It may be considered that the steady-state voltage value across the capacitor C1 is equal to the voltage value of the DC power supply V1. Capacitor C1 is, for example, an electrolytic capacitor or a ceramic capacitor.

The driving switching element T1 is used to drive the sound wave source 11 by controlling power supply to the sound wave source 11. The driving switching element T1 is electrically connected between the sound wave source 11 and ground. The driving switching element T1 is, for example, an n-type MOSFET. Power is supplied to the sound wave source 11 when the driving switching element T1 is on. In FIG. 2, current flows from the capacitor C1 to the sound wave source 11 as indicated by the arrow A1, and the sound wave source 11 is supplied with electric power. If the drive switching element T1 is off, no power is supplied to the sound wave source 11 . The sound wave source 11 generates a sound wave P1 by turning on and off the driving switching element T1. In the present disclosure, a "sound wave" is one cycle of a sine wave. A "series of sound waves", on the other hand, is a sine wave with multiple cycles.

The resistor R1 constitutes an overcurrent protection element electrically connected between the capacitor C1 and the DC power supply V1. Resistor R1 limits the current flowing from DC power supply V1 directly to sound wave source 11 . Excessive heat generation of the sound wave source 11 can be prevented by the resistor R1. The resistance value of the resistor R1 is, for example, 50Ω or more and 5 kΩ or less.

The power auxiliary circuit 13 is provided separately from the DC power supply V1. The power auxiliary circuit 13 supplies power to the drive circuit 12 so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. Used. In other words, the power auxiliary circuit 13 is a circuit for supplementing the lack of power supplied to the sound wave source 11 .

The power auxiliary circuit 13 includes an inductor L1, a charging switching element T2, and a diode D1, as shown in FIG. Inductor L1 is electrically connected between DC power supply V1 and capacitor C1. In FIG. 2, inductor L1 is electrically connected between resistor R1, which is an overcurrent protection element, and DC power supply V1. Charging switching element T2 is electrically connected in parallel to a series circuit of inductor L1 and DC power supply V1. The charging switching element T2 is, for example, an n-type MOSFET. Inductor L1, DC power supply V1, and charging switching element T2 form a closed loop. When the charging switching element T2 is on, energy is stored in the inductor L1. In FIG. 2, current flows through the closed loop of the DC power supply V1, the inductor L1, and the charging switching element T2, and energy is stored in the inductor L1, as indicated by an arrow A2. When the charging switching element T2 is turned off from on, an induced electromotive force is generated in the inductor L1. As a result, current flows from inductor L1 to capacitor C1 as indicated by arrow A3, and capacitor C1 is charged. The power auxiliary circuit 13 of FIG. 2 can charge the capacitor C1 and thereby supply power to the drive circuit 12 . It can also be said that the power auxiliary circuit 13 of FIG. 2 is a charging circuit. Diode D1 is electrically connected between inductor L1 and capacitor C1. Specifically, the anode of diode D1 is electrically connected to inductor L1, and the cathode of diode D1 is electrically connected to capacitor C1. Diode D1 reduces the possibility of inadvertently discharging capacitor C1 by allowing current to flow from capacitor C1 to inductor L1.

The control circuit 14 is configured to control the drive circuit 12 and the power auxiliary circuit 13 . The control circuit 14 has, for example, an oscillator for outputting drive signals S1 and S2, which will be described later. The control circuit 14 is, for example, an integrated circuit such as an FPGA (field-programmable gate array). The control circuit 14 controls the switching of the driving switching element T1 of the drive circuit 12 so that the sound wave source 11 generates a series of sound waves P1, while the control circuit 14 controls the drive circuit 12 so that the power supplied to the sound wave source 11 does not decrease. The power auxiliary circuit 13 is controlled to supply power to the .

The control circuit 14 controls switching (on/off) of the drive switching element T1 of the drive circuit 12. The control circuit 14 controls the driving switching element T1 of the driving circuit 12 to cause the sound wave source 11 to generate a series of sound waves P1. As shown in FIG. 1, the control circuit 14 outputs a driving signal S1 for controlling switching of the driving switching element T1. In this embodiment, the driving switching element T1 is a MOSFET, and the driving signal S1 is input to the gate of the driving switching element T1. While the driving signal S1 is at high level, the driving switching element T1 is turned on. While the driving signal S1 is at low level, the driving switching element T1 is turned off. In FIG. 2, the drive signal S1 is illustrated as a DC power supply.

The control circuit 14 controls switching (on/off) of the charging switching element T2 of the power auxiliary circuit 13. The control circuit 14 controls the charging switching element T2 of the power auxiliary circuit 13 to supply power to the drive circuit 12 so that the power supplied to the sound wave source 11 does not decrease. As shown in FIG. 1, the control circuit 14 outputs a driving signal S2 for controlling switching of the charging switching element T2. In this embodiment, the charging switching element T2 is a MOSFET, and the drive signal S2 is input to the gate of the charging switching element T2. While the driving signal S2 is at high level, the charging switching element T2 is turned on. While the driving signal S2 is at low level, the charging switching element T2 is turned off. In FIG. 2, the drive signal S2 is illustrated as a DC power supply.

Next, the control of the drive circuit 12 and power auxiliary circuit 13 by the control circuit 14 will be described in detail with reference to FIG. FIG. 3 is a timing chart for explaining the operation of the sound wave generator 10. As shown in FIG.

The control circuit 14 outputs a drive signal S1 to the driving switching element T1 in order to control the drive circuit 12 to generate a series of sound waves P1 from the sound wave source 11. The switching frequency of the driving switching element T1 corresponds to the frequency of the series of sound waves P1. The switching frequency of the driving switching element T1 is, for example, 20 kHz or higher. The switching frequency of the driving switching element T1 is, for example, 150 kHz or less. As shown in FIG. 3, the drive signal S1 is a pulse train signal. The period T of the pulse train of the driving signal S1 is set according to the target switching frequency of the driving switching element T1. In FIG. 3, the period T of the drive signal S1 is constant. The length of the driving signal S1 can be, for example, 5 ms to 30 ms. The pulse width of the driving signal S1 is set according to the target duty ratio of the driving switching element T1. A period T in FIG. 3 includes an ON period T1on and an OFF period T1off of the driving switching element T1. The ON period T1on is a period during which the driving switching element T1 is ON. During the ON period T1on, current flows from the capacitor C1 to the sound wave source 11, and power is supplied to the sound wave source 11. FIG. In FIG. 3, the voltage V2 of the capacitor C1 is lowered during the ON period T1on. The off period T1off is a period in which the driving switching element T1 is off. During the off period T1off, no current flows from the capacitor C1 to the sound wave source 11 and power is not supplied to the sound wave source 11 .

As shown in FIG. 3, the voltage V2 of the capacitor C1 decreases due to the ON period T1on. If the voltage V2 of the capacitor C1 continues to drop, sufficient power cannot be supplied to the sound wave source 11 in the next ON period T1on, and the sound wave P1 having the desired sound pressure cannot be obtained. Therefore, the control circuit 14 charges the capacitor C1 by the power auxiliary circuit 13 in order to eliminate the decrease in the voltage V2 of the capacitor C1 due to the ON period T1on, that is, the decrease in the charge amount of the capacitor C1. The control circuit 14 outputs the driving signal S2 to the charging switching element T2 in order to control the power auxiliary circuit 13 and charge the capacitor C1. As shown in FIG. 3, the drive signal S2 is a pulse train signal with a period T. As shown in FIG. In particular, the drive signal S2 is a pulse train signal having the same period (here, T) as that of the corresponding drive signal S1. In FIG. 3, the period T is constant. The pulse width is set according to the target duty ratio of the charging switching element T2. A period T of the drive signal S2 in FIG. 3 includes an ON period T2on and an OFF period T2off of the charging switching element T2. The ON period T2on is a period during which the charging switching element T2 is ON. During the ON period T2on, current flows from the DC power supply V1 to the inductor L1, and energy is stored in the inductor L1. The off period T2off is a period in which the charging switching element T2 is off. During the off period T2off, current flows from the inductor L1 to the capacitor C1, and the capacitor C1 is charged. In the example of FIG. 3, the voltage V2 of the capacitor C1 increases from time t13 and reaches the same value at time t14 at the end of cycle T as at time t11 at the beginning of cycle T. In the example of FIG.

As shown in FIG. 3, the control circuit 14 outputs the driving signal S2 so that the power auxiliary circuit 13 supplies power to the driving circuit 12 during the OFF period T1off of the driving switching element T1. As a result, electric power can be supplied each time the sound wave P1 is generated, and the sound pressure of a series of sound waves P1 can be stabilized. In addition, it is possible to prevent the power from fluctuating while supplying power to the sound wave source 11, thereby stabilizing the sound pressure of the series of sound waves P1. In particular, the control circuit 14 outputs the driving signal S2 so that the power auxiliary circuit 13 charges the capacitor C1 during the OFF period T1off of the driving switching element T1. As a result, the capacitor C1 of the driving circuit 12 is used as the destination of power supply from the power auxiliary circuit 13, so that the sound pressure of the series of sound waves P1 can be stabilized. Specifically, as shown in FIG. 3, the ON period T1on of the driving switching element T1 is set to a period from time t11 to time t12. The OFF period T1off of the driving switching element T1 is set to a period from time t12 to time t14. The ON period T2on of the charging switching element T2 is set to a period from time t11 to time t13 after time t12. Thus, the charging switching element T2 is turned on during the ON period T1on of the driving switching element T1 and turned off during the OFF period T1off of the driving switching element T1. Thereby, the energy stored in the inductor L1 can be increased. In the example of FIG. 3, the driving switching element T1 and the charging switching element T2 are turned on at the same time (see time t11). As a result, the control of the driving switching element T1 and the charging switching element T2 can be simplified. In the example of FIG. 3, the charging switching element T2 is turned off after the driving switching element T1 is turned off. Thereby, the energy stored in the inductor L1 can be increased.

As shown in FIG. 2, the sound wave generator 10 turns on the charging switching element T2 while the capacitor C1 is supplying charge to the sound wave source 11, and during the pulses of the drive signal S1 for the sound wave source 11, to turn off. Thus, the sound wave generator 10 stores energy in the inductor L1 while driving the sound wave source 11, and charges the capacitor C1 with the energy of the inductor L1 after the end of driving the sound wave source 11. FIG. This makes it possible to charge the capacitor C1 for each sound wave P1. Therefore, even when a series of sound waves P1 are output from the sound wave source 11, the series of sound waves P1 can be generated with stable sound pressure without lowering the voltage of the capacitor C1.

In the sound wave generator 10, the power auxiliary circuit 13 is provided to the drive circuit 12 so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. Used to supply power. Here, "no decrease" includes not only no decrease in the strict sense, but also no substantial decrease, that is, a negligible decrease as a whole. In the sound wave generator 10 of the present embodiment, the power auxiliary circuit 13 is configured so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. In order to achieve this, power is supplied to the drive circuit 12 so that the power supplied to the sound wave source 11 is equal to or higher than a specified value. In the present embodiment, the specified value corresponds to the magnitude of power supplied to the sound wave source 11 during the ON period T1on when the voltage V2 of the capacitor C1 is the voltage value Vc in the steady state. In other words, "supplying power to the drive circuit 12 so that the power supplied to the sound wave source 11 is equal to or greater than a specified value" means that the power greater than or equal to the power consumed by the sound wave source 11 due to the generation of the sound wave P1 is supplied to the drive circuit. to supply 12. In this embodiment, this is to supply the capacitor C1 with energy equal to or greater than the energy of the capacitor C1 consumed by the generation of the sound wave P1.

In particular, in the present embodiment, the sound wave generator 10 provides the same amount of energy as the energy consumed by the sound wave source 11 in the capacitor C1 from the inductor L1 to the capacitor C1 every time the sound wave source 11 outputs the sound wave P1. It is set so that That is, the energy released from the capacitor C1 and the energy stored in the inductor L1 are set to match. Below is an example of such a setting.

For example, let Vc be the voltage value in a steady state across the capacitor C1. Let Rth be the resistance value of the sound wave source 11 . Let tAon be the length of the ON period T1on of the driving switching element T1. Let imax be the maximum value of the current IL output from the inductor L1 during the OFF period T2off of the charging switching element T2. Let L be the self-inductance of the inductor L1. When the energy released from capacitor C1 and the energy stored in inductor L1 match, the following equation holds.

Here, when imax, Vc, Rth, and tAon are determined, L is set so as to satisfy the following equation. As a result, the sound pressure of the series of sound waves P1 can be stabilized.

If a DC power supply with a large current capability is used as the DC power supply V1, it is possible to improve the charging speed of the capacitor C1 and reduce the drop in sound pressure. However, a DC power supply with a large current capacity is generally large and expensive. In particular, as the number of series of sound waves P1 increases, the current capability of the DC power supply must also be increased, and there is a limit to the current capability. In particular, in the sound wave generator 10 of the present embodiment, since the electric power for generating the sound wave P1 can be assisted by the power auxiliary circuit 13, a DC power supply with a large current capacity is used as the DC power supply V1. I can do without it. For example, let V be the voltage value of the DC power supply V1. Let tBon be the length of the ON period T2on of the charging switching element T2. Let imax be the maximum value of the current IL output from the inductor L1 during the OFF period T2off of the charging switching element T2. Let L be the self-inductance of the inductor L1. In this case, the DC power supply V1 may be set so as to satisfy the following equation. As a result, the size of the DC power supply V1 can be reduced.

If a capacitor with a large capacitance is used as the capacitor C1, it is possible to store sufficient energy and reduce the drop in sound pressure. However, capacitors with large capacitance are generally large and expensive. In particular, as the number of series of sound waves P1 increases, the capacitance of the capacitor must also increase, and there is a limit to the capacitance. On the other hand, as described above, the current flows from the DC power supply V1 to the inductor L1 during the ON period T2on of the charging switching element T2 to store energy. The energy supplied to the capacitor C1 can be increased by lengthening the length tBon of the ON period T2on of the charging switching element T2, that is, the time (current time) in which the current flows from the DC power supply V1 to the inductor L1. FIG. 4 is a graph showing simulation results of the voltage decay rate ([%]) with respect to the capacitance ([μF]) of the capacitor C1 when the current time is changed. The voltage decay rate indicates, for example, the ratio of the value of the voltage V2 that has decreased in one cycle T to the steady-state value Vc of the voltage V2 of the capacitor C1. As is clear from FIG. 4, the voltage decay rate tends to decrease as the capacitance increases, and the voltage decay rate greatly depends on the current time. In FIG. 4, if the current time is 7 μs or more, the voltage decay rate is 0% even if the capacitance is 100 μF or less. Therefore, by setting the current time, the voltage attenuation rate can be set to 0% regardless of the capacitance of the capacitor C1, and the size of the capacitor C1 can be reduced.

[1-2-2. Receiving device]
The wave receiving device 20 receives a sound wave and outputs a received wave signal indicating the received sound wave to the processing circuit 30 . 1 includes a plurality of (two in the illustrated example) microphones 21, a plurality of (two in the illustrated example) amplifier circuits 22, a plurality of (two in the illustrated example) filters 23, an AD It comprises a converter 24 and a control circuit 25 .

The microphone 21 is an electroacoustic conversion element that converts sound waves into electrical signals. Upon receiving a sound wave, the microphone 21 outputs an analog received wave signal indicating the received sound wave. The microphone 21 is used to detect the sound waves P1 that are reflected by the object after being output from the sound wave source 11 . The amplifier circuit 22 amplifies the received signal in analog format from the microphone 21 and outputs the amplified signal. The filter 23 passes signals in a passband including the frequency band of the sound wave P1. Filter 23 is, for example, a bandpass filter. The AD converter 24 converts the analog received wave signal that has passed through the filter 23 into a digital received wave signal and outputs the digital received wave signal to the control circuit 25 . The microphone 21, the amplifier circuit 22, the filter 23, and the AD converter 24 may have conventionally well-known configurations, so detailed description thereof will be omitted.

The control circuit 25 controls the AD converter 24 so that the AD converter 24 outputs a digital received wave signal to the control circuit 25 . The control circuit 25 outputs the digital received signal from the AD converter 24 to the processing circuit 30 . The control circuit 25 is, for example, an integrated circuit such as FPGA. Note that the control circuit 14 and the control circuit 25 may be integrated into one chip. For example, control circuit 14 and control circuit 25 may be implemented in a single FPGA.

[1-2-3. processing circuit]
The processing circuit 30 is a circuit that controls the operation of the object detection system 1 . The processing circuitry 30 may be implemented by, for example, a computer system including one or more processors (microprocessors) and one or more memories. The functions of the processing circuit 30 are realized by one or more processors executing programs.

The processing circuit 30 uses the sound wave P1 from the sound wave generator 10 to execute object detection processing for detecting an object in the target space. The object detection processing includes wave transmission processing and determination processing. The wave transmission process controls the sound wave generator 10 so that the sound wave generator 10 generates the sound wave P1. The wave transmission process causes the sound wave generator 10 to output a series of sound waves P1 by, for example, sending a measurement start signal to the sound wave generator 10 . The determination process acquires a received wave signal indicating the sound wave received by the wave receiving device 20 from the wave receiving device 20 that receives the sound wave from the target space. In the determination process, for example, a received wave signal in digital format from the wave receiving device 20 is obtained. Determination processing determines whether or not there is an object in the target space based on the acquired received wave signal. In the determination process, for example, if the peak value of the cross-correlation function between the transmitted wave signal and the received wave signal representing the series of sound waves P1 is equal to or greater than a threshold value, it is determined that an object exists in the target space. For example, the main lobe of the cross-correlation function is used as the peak of the cross-correlation function. Further, in the determination processing, when it is determined that there is an object in the target space, the distance to the object is determined based on the received wave signal. In the determination process, for example, the distance to the object is obtained by TOF (Time of Flight) technology based on the time at which the peak of the cross-correlation function between the transmitted wave signal and the received wave signal appears. Conventionally well-known techniques can be applied to the detection of an object and the measurement of the distance to the object using sound waves, so a detailed description thereof will be omitted.

The processing circuit 30 has a function of setting the drive signals S1 and S2 of the control circuit 14 of the sound wave generator 10 .

[1-3. Performance evaluation]
In order to confirm the effect of stabilizing the sound pressure of the series of sound waves P1 by the sound wave generator 10, the sound pressure of the series of sound waves P1 output from the sound wave generator 10 was measured. Also, as a comparative example, a series of sound pressures of sound waves output from a sound wave generator without the power auxiliary circuit 13 was measured. FIG. 5 is a graph showing measurement results of the sound pressure of a series of sound waves P1 output from the sound wave generator 10. As shown in FIG. FIG. 6 is a graph showing measurement results of sound pressure of a series of sound waves output from the sound wave generator of the comparative example.

As shown in FIG. 6, in the sound wave generator of the comparative example, the envelope of the sound pressure of a series of sound waves decreases over time. This is because, in the sound wave generator of the comparative example, a series of sound waves are output from the sound wave source 11 by switching the driving switching element T1, and the charging of the capacitor C1 is insufficient during the OFF period T1off of the driving switching element T1. This is thought to be because When the capacitor C1 is insufficiently charged, the amount of electric charge stored in the capacitor C1 decreases, and the power supplied to the sound wave source 11 decreases. A decrease in the power supplied to the sound wave source 11 contributes to a decrease in the sound pressure of the sound wave, so the sound pressure becomes unstable.

On the other hand, as shown in FIG. 5, in the sound wave generator 10, the sound pressure envelope of the series of sound waves P1 does not decrease. As described above, since the sound wave generator 10 includes the power auxiliary circuit 13, even in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1, the sound wave source 11 Sufficient electric power can be supplied to the sound wave source 11, and a series of sound waves P1 can be output from the sound wave source 11 while suppressing a decrease in sound pressure.

As is clear from FIGS. 5 and 6, according to the sound wave generator 10 of the present embodiment, the sound pressure of a series of sound waves P1 can be stabilized.

[1-4. effects, etc.]
The sound wave generator 10 described above includes a drive circuit 12 and a power auxiliary circuit 13 . The driving circuit 12 has a capacitor C1 charged by a DC power source V1, and a driving switching element T1 that supplies electric power from the capacitor C1 to the sound wave source 11 that generates heat when energized and generates a sound wave P1. The power auxiliary circuit 13 supplies power to the drive circuit 12 so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. In other words, the power auxiliary circuit 13 supplies the driving circuit 12 with power equal to or greater than the power consumed for generating the sound wave P1 each time the sound wave P1 is generated. According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

In addition, in the sound wave generator 10, the power auxiliary circuit 13 supplies power to the drive circuit 12 during the OFF period T1off of the drive switching element T1. According to this configuration, electric power can be supplied each time the sound wave P1 is generated, and the sound pressure of a series of sound waves P1 can be stabilized.

In addition, in the sound wave generator 10, the power auxiliary circuit 13 charges the capacitor C1 during the OFF period T1off of the driving switching element T1. According to this configuration, since the capacitor C1 of the driving circuit 12 is used as the destination of power supply from the power auxiliary circuit 13, the sound pressure of the series of sound waves P1 can be stabilized.

In the sound wave generator 10, the auxiliary power circuit 13 includes an inductor L1 electrically connected between the DC power supply V1 and the capacitor C1, and an inductor L1 electrically connected in parallel with the series circuit of the inductor L1 and the DC power supply V1. It has a charging switching element T2 to be connected. With this configuration, the circuit configuration can be simplified.

In addition, in the sound wave generator 10, the power auxiliary circuit 13 has a diode D1. The anode of diode D1 is electrically connected to inductor L1 and the cathode of diode D1 is electrically connected to capacitor C1. According to this configuration, it is possible to reduce the possibility that the current flows from the capacitor C1 to the inductor L1 and the capacitor C1 unintentionally discharges.

In addition, in the sound wave generator 10, the charging switching element T2 is turned on during the ON period T1on of the driving switching element T1, and turned off during the OFF period T1off of the driving switching element T1. With this configuration, the energy stored in inductor L1 can be increased.

Also, in the sound wave generator 10, the driving switching element T1 and the charging switching element T2 are turned on at the same time. With this configuration, the control of the driving switching element T1 and the charging switching element T2 can be simplified.

Also, in the sound wave generator 10, the charging switching element T2 is turned off after the driving switching element T1 is turned off. With this configuration, the energy stored in inductor L1 can be increased.

In the sound wave generator 10, the voltage value across the capacitor C1 in a steady state is Vc, the resistance value of the sound wave source 11 is Rth, the length of the ON period of the driving switching element T1 is tAon, and the charging switching element If the maximum value of the current IL output from the inductor L1 during the off period T2off of T2 is imax, and the self-inductance of the inductor L1 is L, then L is

meet. According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

In the sound wave generator 10, the voltage value of the DC power source V1 is V, the length of the ON period T2on of the charging switching element T2 is tBon, and the current IL output from the inductor L1 during the OFF period T2off of the charging switching element T2 If imax is the maximum value of and L is the self-inductance of the inductor L1, the DC power supply V1 and the inductor L1 are

is set to satisfy According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

In addition, in the sound wave generator 10, the drive circuit 12 includes an overcurrent protection element (resistor R1) electrically connected between the capacitor C1 and the DC power supply V1. According to this configuration, excessive heat generation of the sound wave source 11 can be prevented.

Also, in the sound wave generator 10, the switching frequency of the drive switching element T1 is 20 kHz or higher. According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

The sound wave generator 10 also includes a control circuit 14 that controls the drive circuit 12 and the power auxiliary circuit 13 . The control circuit 14 controls the switching of the driving switching element T1 of the drive circuit 12 so that the sound wave source 11 generates a series of sound waves P1, while the control circuit 14 controls the drive circuit 12 so that the power supplied to the sound wave source 11 does not decrease. The power auxiliary circuit 13 is controlled to supply power to the . According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

The sound wave generator 10 also includes a drive circuit 12 and a power auxiliary circuit 13 . The driving circuit 12 has a capacitor C1 charged by a DC power source V1, and a driving switching element T1 that supplies electric power from the capacitor C1 to the sound wave source 11 that generates heat when energized and generates a sound wave P1. The power auxiliary circuit 13 includes an inductor L1 electrically connected between the DC power supply V1 and the capacitor C1, and a charging switching element electrically connected in parallel to the series circuit of the inductor L1 and the DC power supply V1. have T2. The power auxiliary circuit 13 supplies power to the drive circuit 12 during the OFF period T1off of the drive switching element T1 in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the drive switching element T1. According to this configuration, the power auxiliary circuit 13 generates a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. can be supplied to the drive circuit 12 . Therefore, the sound pressure of the series of sound waves P1 can be stabilized.

[2. Embodiment 2]
[2-1. Constitution]
FIG. 7 is a block diagram of a configuration example of an object detection system 1A including the sound wave generator 10A according to the second embodiment. As shown in FIG. 7, the object detection system 1A includes a sound wave generator 10A, a wave receiver 20, and a processing circuit 30. As shown in FIG.

FIG. 8 is a circuit diagram of a configuration example of the sound wave generator 10A. As shown in FIGS. 7 and 8, the sound wave generator 10A includes a sound wave source 11 and a plurality of (two in the illustrated example) drive circuits 12-1 and 12-2 (hereinafter collectively denoted by reference numeral 12). , a plurality of (two in the illustrated example) power auxiliary circuits 13-1 and 13-2 (hereinafter collectively denoted by reference numeral 13), and a control circuit 14A. 8, illustration of the control circuit 14A is omitted.

As shown in FIG. 8, each of the drive circuits 12-1 and 12-2 includes a capacitor C1 and a drive switching element T1. The capacitor C1 is electrically connected between the connection point between the DC power source V1 and the acoustic wave source 11 and the ground. Capacitor C1 is charged by DC power supply V1. The capacitors C1 of the drive circuits 12-1 and 12-2 are electrically connected in parallel with each other. The driving switching element T1 is electrically connected between the sound wave source 11 and ground. The driving switching elements T1 of the driving circuits 12-1 and 12-2 are electrically connected in parallel with each other.

As shown in FIGS. 7 and 8, the power auxiliary circuits 13-1 and 13-2 correspond to the drive circuits 12-1 and 12-2, respectively. As shown in FIG. 8, each of the power auxiliary circuits 13-1 and 13-2 includes an inductor L1, a charging switching element T2, and a diode D1. Inductor L1 is electrically connected between DC power supply V1 and capacitor C1. The inductors L1 of the power auxiliary circuits 13-1 and 13-2 are electrically connected in parallel with each other. In each power auxiliary circuit 13, the charging switching element T2 is electrically connected in parallel to the series circuit of the inductor L1 and the DC power supply V1. Inductor L1, DC power supply V1, and charging switching element T2 form a closed loop. Diode D1 of power auxiliary circuit 13-1 is electrically connected between inductor L1 of power auxiliary circuit 13-1 and capacitor C1 of drive circuit 12-1 corresponding to power auxiliary circuit 13-1. Diode D1 of power auxiliary circuit 13-2 is electrically connected between inductor L1 of power auxiliary circuit 13-2 and capacitor C1 of drive circuit 12-2 corresponding to power auxiliary circuit 13-2.

The control circuit 14A is configured to control the drive circuits 12-1 and 12-2 and the power auxiliary circuits 13-1 and 13-2. The control circuit 14 controls the switching of the driving switching elements T1 of the drive circuits 12-1 and 12-2 so as to cause the sound wave source 11 to generate a series of sound waves P1, while the power supplied to the sound wave source 11 decreases. The auxiliary power circuits 13-1 and 13-2 are controlled so as to supply power to the driving circuits 12-1 and 12-2 so as not to cause the power failure. In particular, the control circuit 14A sequentially uses the set of drive circuit 12-1 and power auxiliary circuit 13-1 and the set of drive circuit 12-2 and power auxiliary circuit 13-2.

The control circuit 14 outputs a plurality of drive signals S1-1 and S1-2 (hereinafter collectively referred to as S1) for controlling switching of the drive switching elements T1 of the drive circuits 12-1 and 12-2. ). In FIG. 8, the driving switching element T1 is a MOSFET, and the driving signal S1 is input to the gate of the driving switching element T1. In FIG. 8, drive signals S1-1 and S1-2 are illustrated as DC power sources.

The control circuit 14 outputs a plurality of drive signals S2-1 and S2-2 (hereinafter collectively referred to as S2) for controlling switching of the charging switching elements T2 of the power auxiliary circuits 13-1 and 13-2. attached) is output. In FIG. 8, the charging switching element T2 is a MOSFET, and the drive signal S2 is input to the gate of the charging switching element T2. In FIG. 8, drive signals S2-1 and S2-2 are illustrated as DC power sources.

Next, the control of the drive circuit 12 and power auxiliary circuit 13 by the control circuit 14A will be described in detail with reference to FIG. FIG. 9 is a timing chart for explaining the operation of the sound wave generator 10A.

The control circuit 14A applies a plurality of drive signals S1-1, S1-2 to the plurality of drive circuits 12-1, 12-2 to control the drive circuit 12 to generate a series of sound waves P1 from the sound wave source 11. Output to the driving switching element T1. The plurality of drive signals S1-1 and S1-2 are set so that the drive switching elements T1 of the plurality of drive circuits 12-1 and 12-2 cooperate to generate a series of sound waves P1 from the sound wave source 11. be done. In particular, the control circuit 14A generates a series of sound waves P1 from the sound wave source 11 by sequentially switching the driving switching elements T1 of the drive circuits 12-1 and 12-2. -1, S1-2 are set. In FIG. 9, S0 indicates a composite drive signal obtained by combining a plurality of drive signals S1-1 and S1-2, and the period and length of the composite drive signal S0 correspond to the period and length of the series of sound waves P1. is set to correspond to As shown in FIG. 9, the combined drive signal S0 is a pulse train signal with a period T. As shown in FIG. The period T corresponds to the period of the series of sound waves P1. As described above, the combined drive signal S0 is a combined drive signal obtained by combining a plurality of drive signals S1-1 and S1-2. In FIG. 9, each of drive signals S1-1 and S1-2 is a pulse train having a period twice (2T) the period of combined drive signal S0. The drive signals S1-1 and S1-2 are shifted by the period T of the combined drive signal S0, thereby obtaining the combined drive signal S0 shown in FIG. It should be noted that the periods of the plurality of drive signals S1 and the phase shifts of the plurality of drive signals S1 may be appropriately set, and are not limited to the example shown in FIG.

The cycle of the driving signal S1-1 includes an ON period T1on-1 and an OFF period T1off-1 of the driving switching element T1 of the driving circuit 12-1. During the ON period T1on-1, a current flows from the capacitor C1 of the driving circuit 12-1 to the sound wave source 11, and the sound wave source 11 is supplied with power. During the off period T1off-1, no current flows from the capacitor C1 of the drive circuit 12-1 to the sound wave source 11, and power is not supplied from the drive circuit 12-1 to the sound wave source 11. FIG. The period of the driving signal S1-2 includes an ON period T1on-2 and an OFF period T1off-2 of the driving switching element T1 of the driving circuit 12-2. During the ON period T1on-2, current flows from the capacitor C1 of the drive circuit 12-2 to the sound wave source 11, and power is supplied to the sound wave source 11. FIG. During the off period T1off-2, no current flows from the capacitor C1 of the drive circuit 12-2 to the sound wave source 11, and power is not supplied from the drive circuit 12-2 to the sound wave source 11. FIG.

The control circuit 14A alternately supplies power to the sound wave source 11 from the capacitors C1 of the drive circuits 12-1 and 12-2.

The control circuit 14A controls the power auxiliary circuits 13-1 and 13-2 to eliminate the drop in the voltage V2 of the capacitors C1 of the drive circuits 12-1 and 12-2 due to the on-periods T1on-1 and T1on-2. Charge the corresponding capacitor C1. The control circuit 14A applies drive signals S2-1 and S2-2 to the power auxiliary circuits 13-1 and 13-2 to control the power auxiliary circuits 13-1 and 13-2 to charge the corresponding capacitors C1. is output to the charging switching element T2. The control circuit 14A controls the power supplied to the sound wave source 11 in the operation of generating a series of sound waves P1 from the sound wave source 11 by sequentially switching the driving switching elements T1 of the plurality of drive circuits 12-1 and 12-2. The plurality of drive signals S2-1 and S2-2 are set so that the plurality of power auxiliary circuits 13-1 and 13-2 supply power to the corresponding plurality of drive circuits 12, respectively, so as not to decrease the power. As a result, each of the plurality of power auxiliary circuits 13-1 and 13-2 sequentially switches the driving switching elements T1 of the plurality of drive circuits 12-1 and 12-2 to generate a series of sound waves from the sound wave source 11. is supplied to the corresponding driving circuit 12 of the plurality of driving circuits 12-1 and 12-2 during the off period T1off of the driving switching element T1 of the corresponding driving circuit 12.

As shown in FIG. 9, the drive signals S2-1 and S2-2 are pulse train signals having the same period (here, 2T) as the corresponding drive signals S1-1 and S1-2. The pulse width is set according to the target duty ratio of the charging switching element T2. The period of the drive signal S2-1 includes an ON period T2on-1 and an OFF period T2off-1 of the charging switching element T2 of the power auxiliary circuit 13-1. During the ON period T2on-1, a current flows from the DC power supply V1 to the inductor L1 of the power auxiliary circuit 13-1, and energy is stored in the inductor L1 of the power auxiliary circuit 13-1. During the OFF period T2off-1, current flows from the inductor L1 of the power auxiliary circuit 13-1 to the capacitor C1 of the drive circuit 12-1, and the capacitor C1 of the drive circuit 12-1 is charged. The cycle of the driving signal S2-2 includes an ON period T2on-2 and an OFF period T2off-2 of the charging switching element T2 of the power auxiliary circuit 13-2. During the ON period T2on-2, current flows from the DC power supply V1 to the inductor L1 of the power auxiliary circuit 13-2, and energy is stored in the inductor L1 of the power auxiliary circuit 13-2. During the OFF period T2off-2, a current flows from the inductor L1 of the power auxiliary circuit 13-2 to the capacitor C1 of the drive circuit 12-2, and the capacitor C1 of the drive circuit 12-2 is charged.

As shown in FIG. 9, the control circuit 14A controls the power auxiliary circuits 13-1 and 13-2 to supply power to the driving circuits 12-1 and 12-2 during the OFF periods T1off-1 and T1off-2. It outputs drive signals S2-1 and S2-2. As a result, electric power can be supplied each time the sound wave P1 is generated, and the sound pressure can be stabilized. In addition, it is possible to prevent power from fluctuating while power is being supplied to the sound wave source 11, thereby stabilizing the sound pressure. The control circuit 14A outputs the drive signal S2-1 so that the power auxiliary circuits 13-1 and 13-2 charge the capacitors C1 of the drive circuits 12-1 and 12-2 during the off periods T1on-1 and T1on-2, respectively. , S2-2. As a result, the capacitor C1 of the drive circuit 12 corresponding to the power supply destination from the power auxiliary circuit 13 is used, so that the sound pressure can be stabilized.

Specifically, as shown in FIG. 9, the ON period T1on-1 is set to the period from time t21 to t22, and the OFF period T1off-1 is set to the period from time t22 to time t26. The ON period T2on-1 is set to a period from time t21 to time t24 after time t22. Thus, the charging switching element T2 of the power auxiliary circuit 13-1 is turned on during the on period T1on-1 and turned off during the off period T1off-1. Thereby, the energy stored in the inductor L1 of the power auxiliary circuit 13-1 can be increased. In particular, since the period 2T of the drive signal S1-1 is longer than the period T of the combined drive signal S0, the ON period T2on-1 can be made longer than the period of the combined drive signal S0. Therefore, the energy stored in the inductor L1 of the power auxiliary circuit 13-1 can be further increased.

As shown in FIG. 9, the ON period T1on-2 is set to the period from time t23 to time t25, and the OFF period T1off-2 is set to the period from time t25 to time t28. The ON period T2on-2 is set to a period from time t23 to time t27 after time t25. Thus, the charging switching element T2 of the power auxiliary circuit 13-2 is turned on during the on period T1on-2 and turned off during the off period T1off-2. Thereby, the energy stored in the inductor L1 of the power auxiliary circuit 13-2 can be increased. In particular, since the period 2T of the drive signal S1-2 is longer than the period T of the combined drive signal S0, the ON period T2on-2 can be made longer than the period of the combined drive signal S0. Therefore, the energy stored in the inductor L1 of the power auxiliary circuit 13-2 can be further increased.

In the present embodiment, the sound wave generator 10A operates to generate a series of sound waves P1 from the sound wave source 11 by sequentially switching the driving switching elements T1 of the plurality of drive circuits 12 . In this embodiment, the sound wave generator 10A includes two drive circuits 12-1 and 12-2, and alternately supplies power to the sound wave source 11 from the two drive circuits 12-1 and 12-2. In the operation of generating a series of sound waves P1 in this way, the power auxiliary circuits 13 supply power to the corresponding drive circuits 12 such that the power supplied to the sound wave source 11 is not reduced. In this embodiment, the auxiliary power circuit 13-1 supplies power to the driving circuit 12-1, and the auxiliary power circuit 13-2 supplies power to the driving circuit 12-2.

As described above, in the present embodiment, the driving switching elements T1 of the plurality of driving circuits 12 are switched in order, thereby causing the sound wave source 11 to generate a series of sound waves P1. Therefore, the ON period T2on of the charging switching element T2 in each power auxiliary circuit 13 can be made longer than the cycle of the series of sound waves P1. That is, by providing a plurality of sets of the drive circuit 12 and the power auxiliary circuit 13, the ON period T2on of the charging switching element T2 can be made longer than the period of the series of sound waves P1, and the ON period T2on of the charging switching element T2 can be increased. In addition, the energy that can be stored in inductor L1 can be increased.

[2-2. effects, etc.]
The sound wave generator 10A described above includes a plurality of drive circuits 12 and a plurality of power auxiliary circuits 13 corresponding to the plurality of drive circuits 12, respectively. The plurality of power auxiliary circuits 13 do not reduce the power supplied to the sound wave source 11 in the operation of generating a series of sound waves P1 from the sound wave source 11 by sequentially switching the driving switching elements T1 of the plurality of drive circuits 12. , power is supplied to a plurality of drive circuits 12 corresponding to each other. According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

In other words, the sound wave generator 10A includes a plurality of drive circuits 12 and a plurality of power auxiliary circuits 13 corresponding to the plurality of drive circuits 12, respectively. Each of the plurality of power auxiliary circuits 13 is operated to generate a series of sound waves from the sound wave source 11 by sequentially switching the driving switching elements T1 of the plurality of drive circuits 12. The power is supplied to the corresponding drive circuit 12 during the OFF period T1off of the drive switching element T1 of the corresponding drive circuit 12 . According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

[3. Embodiment 3]
[3-1. Constitution]
FIG. 10 is a block diagram of a configuration example of an object detection system 1B including a sound wave generator 10B according to the third embodiment. As shown in FIG. 10, the object detection system 1B includes a sound wave generator 10B, a wave receiver 20, and a processing circuit 30. As shown in FIG.

FIG. 11 is a circuit diagram of a configuration example of the sound wave generator 10B. As shown in FIGS. 10 and 11, the sound wave generator 10B includes a sound wave source 11, a drive circuit 12, a power auxiliary circuit 13B, and a control circuit 14B. 11, illustration of the control circuit 14B is omitted.

The power auxiliary circuit 13B supplies power to the driving circuit 12 so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. Used.

The power auxiliary circuit 13B includes a plurality of auxiliary capacitors C2-1 to C2-n, a switching circuit 131, and a plurality of auxiliary resistors R2-1 to R2-n.

A plurality of auxiliary capacitors C2-1 to C2-n are charged by a plurality of auxiliary DC power supplies V2-1 to V2-n, respectively. Auxiliary capacitors C2-1 to C2-n are used to power the acoustic wave source 11 instead of the capacitor C1. The auxiliary capacitors C2-1 to C2-n are electrically connected between the connection points between the auxiliary DC power sources V2-1 to V2-n and the sound wave source 11 and the ground. Auxiliary capacitors C2-1 to C2-n are charged by auxiliary DC power supplies V2-1 to V2-n. It can be considered that the voltage values across the auxiliary capacitors C2-1 to C2-n in the steady state are equal to the voltage values of the auxiliary DC power supplies C2-1 to C2-n. The auxiliary capacitors C2-1 to C2-n are, for example, electrolytic capacitors or ceramic capacitors.

The auxiliary DC power supplies V2-1 to V2-n are composed of various power supply circuits and/or batteries. Various power supply circuits include, for example, AC/DC converters, DC/DC converters, regulators, and batteries. The voltage value of the auxiliary DC power supply V2 is, for example, 5V.

The auxiliary resistors R2-1 to R2-n constitute overcurrent protection elements electrically connected between the auxiliary capacitors C2-1 to C2-n and the auxiliary DC power supplies V2-1 to V2-n. Auxiliary resistors R2-1 to R2-n limit the current that flows directly to sound wave source 11 from auxiliary DC power supplies V2-1 to V2-n. Excessive heat generation of the sound wave source 11 can be prevented by the auxiliary resistors R2-1 to R2-n. The resistance values of the auxiliary resistors R2-1 to R2-n are, for example, 50Ω or more and 5 kΩ or less.

The switching circuit 131 selects the power supply source for the sound wave source 11 from the capacitor C1 of the drive circuit 12 and the plurality of auxiliary capacitors C2-1 to C2-n of the power auxiliary circuit 13B. More specifically, the switching circuit 131 controls the capacitor of the drive circuit 12 so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. At least one of the one or more auxiliary capacitors C2-1 to C2-n is electrically connected to the acoustic wave source 11 instead of C1. According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

The switching circuit 131, as shown in FIG. 11, includes a main switch SW1 and a plurality of auxiliary switches SW2-1 to SW2-n. Main switch SW1 is electrically connected between sound wave source 11 and capacitor C1. The plurality of auxiliary switches SW2-1 to SW2-n are electrically connected between the sound wave source 11 and the plurality of auxiliary capacitors C2-1 to C2-n, respectively. In the switching circuit 131, one of the main switch SW1 and the plurality of auxiliary switches SW2-1 to SW2-n is turned on, and the rest are turned off. Thereby, the capacitor C1 of the drive circuit 12 and one of the auxiliary capacitors C2-1 to C2-n of the power auxiliary circuit 13B are electrically connected to the sound wave source 11. FIG.

The control circuit 14B is configured to control the drive circuit 12 and the power auxiliary circuit 13B.

The control circuit 14B controls switching (on/off) of the drive switching element T1 of the drive circuit 12. The control circuit 14B controls the driving switching element T1 of the driving circuit 12, thereby causing the sound wave source 11 to generate a series of sound waves P1. As shown in FIG. 10, the control circuit 14 outputs a driving signal S1 for controlling switching of the driving switching element T1. In this embodiment, the driving switching element T1 is a MOSFET, and the driving signal S1 is input to the gate of the driving switching element T1. In FIG. 11, the drive signal S1 is illustrated as a DC power supply.

The control circuit 14B controls the switching circuit 131 of the power auxiliary circuit 13B. The control circuit 14B supplies power to the driving circuit 12 by controlling the main switch SW1 and the plurality of auxiliary switches SW2-1 to SW2-n of the switching circuit 131 so that the power supplied to the sound wave source 11 does not decrease. perform the action to be performed. In this embodiment, the control circuit 14B includes one or more auxiliary capacitors C2-1 to C2-n instead of the capacitor C1 of the drive circuit 12 so that the voltage VT applied to the sound wave source 11 does not fall below a predetermined value. are electrically connected to the acoustic wave source 11 . More specifically, the control circuit 14B controls the capacitor C1 of the drive circuit 12 and the plurality of auxiliary capacitors C2-1 to C2- n are electrically connected to the acoustic wave source 11 . The predetermined value is set so that the power supplied to the sound wave source 11 does not decrease. That is, the control circuit 14B sequentially uses the capacitor C1 of the drive circuit 12 and the plurality of auxiliary capacitors C2-1 to C2-n of the power auxiliary circuit 13B so that the power supplied to the sound wave source 11 does not decrease. to

Next, the control of the power auxiliary circuit 13B by the control circuit 14B will be described in detail with reference to FIG. FIG. 12 is a timing chart for explaining the operation of the sound wave generator 10. FIG. As shown in FIG. 12, the control circuit 14B provides a drive signal S31 for controlling the main switch SW1 of the switching circuit 131 and a drive signal S31 for controlling the plurality of auxiliary switches SW2-1 to SW2-n of the switching circuit 131. It outputs drive signals S32-1 to S32-n (hereinafter collectively referred to as S32). While the drive signal S31 is at high level, the main switch SW1 is turned on. While the drive signal S31 is at low level, the main switch SW1 is turned off. While the drive signal S32 is at high level, the auxiliary switch SW2 is turned on. While the drive signal S32 is at low level, the auxiliary switch SW2 is turned off.

At time t31, the control circuit 14B sets the drive signal S31 to high level, sets the drive signals S32-1 to S32-n to low level, and turns on only the main switch SW1. As a result, only the capacitor C1 of the drive circuit 12 is electrically connected to the sound wave source 11, and power can be supplied from the capacitor C1 to the sound wave source 11. FIG. The voltage VT applied to the sound wave source 11 at time t31 is equal to the voltage across the capacitor C1. While the driving switching element T1 is switched to generate a series of sound waves P1 from the sound wave source 11, the energy stored in the capacitor C1 is consumed and the voltage VT drops.

After time t31, the control circuit 14B sets the drive signal S32-1 to high level and sets the drive signals S31, S32-2 to S32-n to low level at time t32-1 before the voltage VT becomes equal to or lower than a predetermined value, Only the auxiliary switch SW2-1 is turned on. As a result, only the auxiliary capacitor C2-1 of the power auxiliary circuit 13 is electrically connected to the sound wave source 11, and power can be supplied to the sound wave source 11 from the auxiliary capacitor C2-1. Therefore, the voltage VT applied to the sound wave source 11 at time t32-1 becomes equal to the voltage across the auxiliary capacitor C2-1. While the driving switching element T1 is switched to generate a series of sound waves P1 from the sound wave source 11, the energy accumulated in the auxiliary capacitor C2-1 is consumed and the voltage VT drops.

After time t32-1, the control circuit 14B sets the drive signal S32-2 to a high level at time t32-2 before the voltage VT becomes equal to or lower than a predetermined value, and sets the drive signals S31, S32-1, S32-3 to S32. -n is set to low level, and only the auxiliary switch SW2-2 is turned on. As a result, only the auxiliary capacitor C2-2 of the power auxiliary circuit 13 is electrically connected to the sound wave source 11, and electric power can be supplied to the sound wave source 11 from the auxiliary capacitor C2-2. Therefore, the voltage VT applied to the sound wave source 11 at time t32-2 becomes equal to the voltage across the auxiliary capacitor C2-2. While the driving switching element T1 is switched to generate a series of sound waves P1 from the sound wave source 11, the energy accumulated in the auxiliary capacitor C2-2 is consumed, and the voltage VT decreases.

, t32-n-1, t32-n before the voltage VT becomes equal to or less than the predetermined value, the control circuit 14B controls the drive signals S32-3, . -n is set to a high level, and only the auxiliary switches SW2-3, . . . , SW2-n-1 and SW2-n are turned on.

In this manner, the control circuit 14B turns on one of the main switch SW1 and the plurality of auxiliary switches SW2-1 to SW2-n so that the voltage VT applied to the sound wave source 11 does not fall below a predetermined value. drive signals 31, 32-1, 32-n are output so that

Therefore, even when the sound wave generator 10B outputs a series of sound waves P1 from the sound wave source 11, the power supplied to the sound wave source 11 can be prevented from decreasing, and the series of sound waves P1 can be generated at a stable sound pressure. can be generated.

[3-2. effects, etc.]
In the sound wave generator 10B described above, the power auxiliary circuit 13B includes a plurality of auxiliary capacitors C2-1 to C2-n charged by a plurality of auxiliary DC power sources V2-1 to V2-n, respectively, and a switching circuit 131. Prepare. The switching circuit 131 replaces the capacitor C1 of the drive circuit 12 with a plurality of capacitors C1 so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. at least one of the auxiliary capacitors C2-1 to C2-n is electrically connected to the acoustic wave source 11; According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

(Modification)
Embodiments of the present disclosure are not limited to the above embodiments. The above-described embodiment can be modified in various ways according to the design, etc., as long as the subject of the present disclosure can be achieved. Modifications of the above embodiment are listed below. Modifications described below can be applied in combination as appropriate.

In Embodiment 1, the frequency of the series of sound waves P is constant, but the frequency does not necessarily have to be constant. For example, the series of sound waves P may vary in frequency (eg, increase or decrease) over time. FIG. 12 is a waveform diagram for explaining the operation of the sound wave generator of one modification. In FIG. 12, the driving signal S1 is a pulse signal whose frequency decreases (period increases) with time. In FIG. 12, the cycle of the drive signal S1 increases to T41, T42, T43, . In FIG. 12, the ON period T1on is constant, but the OFF period T1off increases as the cycle increases. The drive signal S1 may be a pulse signal whose frequency increases (period decreases) with time. That is, the drive signal S1 may be a pulse signal whose frequency increases or decreases with time. Such a signal is called, for example, a chirp signal. Using a chirp signal can reduce the side lobes of the cross-correlation function compared to using a pulse signal whose frequency does not change with time. Therefore, the main lobe of the cross-correlation function can be easily distinguished from the side lobes, and the accuracy of object detection can be improved.

In FIG. 12, the drive signal S2 is synchronized with the drive signal S1. Therefore, the period of the drive signal S2 is equal to the period of the drive signal S1. If the ON period T2on of the drive signal S2 is long, more energy can be stored in the inductor L1 of the power auxiliary circuit 13. FIG. From this point, the ON period T2on of the drive signal S2 may be set according to the cycle of the drive signal S1. In FIG. 12, since the cycle of the drive signal S1 is increased, the ON period T2on of the drive signal S2 is also increased. Thus, the ON period T2on of the drive signal S2 may not be constant, and may be set according to the cycle of the drive signal S1.

In Embodiment 2, the sound wave generator 10A includes two sets of drive circuit 12 and power auxiliary circuit 13, but the number of sets of drive circuit 12 and power auxiliary circuit 13 may be three or more. . In a modified example, the sound wave generator 10A may operate to generate a series of sound waves P1 from the sound wave source 11 by sequentially switching the driving switching elements T1 of the plurality of drive circuits 12 . Then, in the operation of generating a series of sound waves P1, the plurality of power auxiliary circuits 13 may supply power to the corresponding plurality of drive circuits 12 so that the power supplied to the sound wave source 11 does not decrease.

In Embodiment 3, the number of auxiliary DC power supplies V2-1 to V2-n and the number of auxiliary capacitors C2-1 to C2-n are not particularly limited. In one modification, the power auxiliary circuit 13B includes one or more auxiliary capacitors C2-1 to C2-n charged by one or more auxiliary DC power supplies V2-1 to V2-n, respectively, and a switching circuit 131. good. The switching circuit 131 replaces the capacitor C1 of the drive circuit 12 with 1 so that the power supplied to the sound wave source 11 does not decrease in the operation of generating a series of sound waves P1 from the sound wave source 11 by switching the driving switching element T1. At least one of the above auxiliary capacitors C2-1 to C2-n may be electrically connected to the sound wave source 11. FIG. According to this configuration, the sound pressure of the series of sound waves P1 can be stabilized.

In one variation, another overcurrent protection element may be used instead of resistor R1. Examples of overcurrent protection elements include current fuses, fuse resistors, bimetals, and the like. Also, an overcurrent protection device is not essential.

(Mode)
As is clear from the above embodiments and modifications, the present disclosure includes the following aspects. In the following, reference numerals are attached with parentheses only for the purpose of clarifying correspondence with the embodiments.

A first aspect is a sound wave generator (10; 10A; 10B) comprising a drive circuit (12) and a power auxiliary circuit (13; 13B). The drive circuit (12) supplies electric power from the capacitor (C1) to a capacitor (C1) charged by a DC power supply (V1) and to a sound wave source (11) that generates heat by energization and generates a sound wave (P1). It has a driving switching element (T1) for supplying power. The power auxiliary circuit (13; 13B) is supplied to the sound wave source (11) in operation to generate a series of sound waves (P1) from the sound wave source (11) by switching the driving switching element (T1). The drive circuit (12) is powered so that the power does not decrease. According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

The second aspect is a sound wave generator (10; 10A) based on the first aspect. In the second aspect, the power auxiliary circuit (13) supplies power to the drive circuit (12) during an OFF period (T1off) of the driving switching element (T1). According to this aspect, electric power can be supplied each time the sound wave (P1) is generated, and the sound pressure can be stabilized.

A third aspect is a sound wave generator (10; 10A) based on the second aspect. In the third aspect, the power auxiliary circuit (13) charges the capacitor (C1) during an OFF period (T1off) of the driving switching element (T1). According to this aspect, since the capacitor (C1) of the drive circuit (12) is used as the destination of power supply from the power auxiliary circuit (13), power is supplied to the sound wave source (11) via the capacitor (C1). It is possible to stabilize the sound pressure.

A fourth aspect is a sound wave generator (10; 10A) based on the third aspect. In the fourth aspect, the power auxiliary circuit (13) includes an inductor (L1) electrically connected between the DC power supply (V1) and the capacitor (C1), the inductor (L1) and the and a charging switching element (T2) electrically connected in parallel to a series circuit with the DC power supply (V1). According to this aspect, the circuit configuration can be simplified.

A fifth aspect is a sound wave generator (10; 10A) comprising a drive circuit (12) and a power auxiliary circuit (13). The drive circuit (12) supplies electric power from the capacitor (C1) to a capacitor (C1) charged by a DC power supply (V1) and to a sound wave source (11) that generates heat by energization and generates a sound wave (P1). It has a driving switching element (T1) for supplying power. The power auxiliary circuit (13) includes an inductor (L1) electrically connected between the DC power supply (V1) and the capacitor (C1), and the inductor (L1) and the DC power supply (V1). and a charging switching element (T2) electrically connected in parallel to the series circuit of . The power auxiliary circuit (13) generates a series of sound waves (P1) from the sound wave source (11) by switching the driving switching element (T1) during an OFF period ( T1off) powers the drive circuit (12). According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

A sixth aspect is a sound wave generator (10; 10A) based on the fourth or fifth aspect. In a sixth aspect, said power auxiliary circuit (13) comprises a diode (D1). The anode of the diode (D1) is electrically connected to the inductor (L1) and the cathode of the diode (D1) is electrically connected to the capacitor (C1). According to this aspect, it is possible to reduce the possibility that a current flows from the capacitor (C1) to the inductor (L1) and the capacitor (C1) is unintentionally discharged.

A seventh aspect is a sound wave generator (10; 10A) based on any one of the fourth to sixth aspects. In the sixth aspect, the charging switching element (T2) is turned on during an ON period (T1on) of the driving switching element (T1), and an OFF period (T1off) of the driving switching element (T1). turned off at According to this aspect, the energy stored in the inductor (L1) can be increased.

An eighth aspect is a sound wave generator (10; 10A) based on the seventh aspect. In the eighth aspect, the driving switching element (T1) and the charging switching element (T2) are turned on at the same time. According to this aspect, the control of the driving switching element (T1) and the charging switching element (T2) can be simplified.

A ninth aspect is a sound wave generator (10; 10A) based on the eighth aspect. In the ninth aspect, the charging switching element (T2) is turned off after the driving switching element (T1) is turned off. According to this aspect, the energy stored in the inductor (L1) can be increased.

A tenth aspect is a sound wave generator (10; 10A) according to any one of the fourth to ninth aspects. In the tenth aspect, the voltage value in a steady state across the capacitor (C1) is Vc, the resistance value of the sound wave source (11) is Rth, and the length of the ON period of the driving switching element (T1) is tAon, the maximum value of the current (IL) output from the inductor (L1) during the OFF period (T2off) of the charging switching element (T2) is imax, and the self-inductance of the inductor (L1) is L, L is

meet. According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

An eleventh aspect is a sound wave generator (10; 10A) according to any one of the fourth to tenth aspects. In the eleventh aspect, the voltage value of the DC power supply (V1) is V, the length of the ON period (T2on) of the charging switching element (T2) is tBon, and the OFF period (T2) of the charging switching element (T2) is T2off), the maximum value of the current (IL) output from the inductor (L1) is imax, and the self-inductance of the inductor (L1) is L, the DC power supply (V1) and the inductor (L1) are:

is set to satisfy According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

A twelfth aspect is a sound wave generator (10) based on any one of the first to eleventh aspects. In the twelfth aspect, the drive circuit (12) comprises an overcurrent protection element (R1) electrically connected between the capacitor (C1) and the DC power supply (V1). According to this aspect, excessive heat generation of the sound wave source (11) can be prevented.

A thirteenth aspect is a sound wave generator (10A) based on any one of the first to twelfth aspects. In the thirteenth aspect, the sound wave generator (10A) includes a plurality of the drive circuits (12) and a plurality of the power auxiliary circuits (13; 13B) respectively corresponding to the plurality of drive circuits (12). Prepare. The plurality of power auxiliary circuits (13; 13B) generate a series of sound waves (P1) from the sound wave source (11) by sequentially switching the driving switching elements (T1) of the plurality of drive circuits (12). Power is supplied to each of the plurality of drive circuits (12) so that the power supplied to the sound wave source (11) does not decrease in the generating operation. According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

A fourteenth aspect is a sound wave generator (10A) based on the fifth aspect. In the fourteenth aspect, the sound wave generator (10A) includes a plurality of the drive circuits (12) and a plurality of the power auxiliary circuits (13; 13B) respectively corresponding to the plurality of drive circuits (12). Prepare. Each of the plurality of power auxiliary circuits (13; 13B) generates a series of sound waves (P1 ) in the driving circuit (12) corresponding to the plurality of driving circuits (12), during the OFF period (T1off) of the driving switching element (T1) of the corresponding driving circuit (12), supply power. According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

A fifteenth aspect is a sound wave generator (10B) based on the first aspect. In the fifteenth aspect, the power auxiliary circuit (13B) includes one or more auxiliary capacitors (C2-1 to C2-n) each charged by one or more auxiliary DC power supplies (V2-1 to V2-n) and , and a switching circuit (131). The switching circuit (131) reduces the power supplied to the sound wave source (11) in the operation of generating a series of sound waves (P1) from the sound wave source (11) by switching the driving switching element (T1). At least one of the one or more auxiliary capacitors (C2-1 to C2-n) is electrically connected to the sound wave source (11) instead of the capacitor (C1) of the drive circuit (12) so as not to . According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

A sixteenth aspect is a sound wave generator (10; 10A; 10B) based on any one of the first to fifteenth aspects. In the sixteenth aspect, the switching frequency of the driving switching element (T1) is 20 kHz or more. According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

A seventeenth aspect is a sound wave generator (10; 10A; 10B) based on any one of the first to sixteenth aspects. In a seventeenth aspect, the sound wave generator (10; 10A; 10B) comprises a control circuit (14; 14A) that controls the drive circuit (12) and the power auxiliary circuit (13; 13B). The control circuit (14; 14A) controls the switching of the driving switching element (T1) of the driving circuit (12) so as to cause the sound wave source (11) to generate a series of sound waves (P1), while the The power auxiliary circuit (13; 13B) is controlled to supply power to the driving circuit (12) so that the power supplied to the sound wave source (11) does not decrease. According to this aspect, the sound pressure of the series of sound waves (P1) can be stabilized.

The present disclosure is applicable to sound wave generators. Specifically, the present disclosure is applicable to a sound wave generator that supplies power from a capacitor to a sound wave source that generates heat and generates sound waves when energized.

10, 10A, 10B sound wave generator 11 sound wave source 12 drive circuit C1 capacitor T1 drive switching

element R1 resistor

13, 13B power auxiliary circuit C2-1 to C2-n auxiliary capacitor L1 inductor T2 charging switching

element D1 diode

14, 14A Control circuit V1 DC power supply V2-1 to V2-n Auxiliary DC power supply P1 Sound wave

Claims

a driving circuit having a capacitor charged by a DC power supply and a driving switching element for supplying electric power from the capacitor to a sound wave source that generates heat by energization and generates a sound wave;
a power auxiliary circuit that supplies power to the drive circuit so that the power supplied to the sound wave source does not decrease in the operation of generating a series of sound waves from the sound wave source by switching the driving switching element;
comprising
Sonic generator.
The power auxiliary circuit supplies power to the drive circuit during an OFF period of the drive switching element.
The sound wave generator according to claim 1.
The power auxiliary circuit charges the capacitor during an OFF period of the drive switching element.
The sound wave generator according to claim 2.
The power auxiliary circuit is
an inductor electrically connected between the DC power supply and the capacitor;
a charging switching element electrically connected in parallel to a series circuit of the inductor and the DC power supply;
having
The sound wave generator according to claim 3.
a driving circuit having a capacitor charged by a DC power supply and a driving switching element for supplying electric power from the capacitor to a sound wave source that generates heat by energization and generates a sound wave;
an inductor electrically connected between the DC power supply and the capacitor; and a charging switching element electrically connected in parallel to a series circuit of the inductor and the DC power supply, a power auxiliary circuit for supplying power to the driving circuit during an OFF period of the driving switching element in the operation of generating a series of sound waves from the sound wave source by switching the switching element;
comprising
Sonic generator.
The power auxiliary circuit has a diode,
an anode of the diode is electrically connected to the inductor;
the cathode of the diode is electrically connected to the capacitor;
The sound wave generator according to claim 4 or 5.
The charging switching element is turned on during an on period of the driving switching element and turned off during an off period of the driving switching element.
The sound wave generator according to any one of claims 4 to 6.
the driving switching element and the charging switching element are turned on at the same time;
The sound wave generator according to claim 7.
the charging switching element is turned off after the driving switching element is turned off;
The sound wave generator according to claim 8.
Vc is the steady-state voltage across the capacitor, Rth is the resistance value of the sound wave source, tAon is the length of the ON period of the driving switching element, and output from the inductor during the OFF period of the charging switching element Let imax be the maximum value of the applied current and L be the self-inductance of the inductor, then L is

satisfy the
The sound wave generator according to any one of claims 4 to 9.
V is the voltage of the DC power supply, tBon is the length of the ON period of the charging switching element, imax is the maximum value of the current output from the inductor during the OFF period of the charging switching element, and the self-inductance of the inductor is L, the DC power supply is

is set to satisfy
The sound wave generator according to any one of claims 4-10.
The drive circuit includes an overcurrent protection element electrically connected between the capacitor and the DC power supply.
The sound wave generator according to any one of claims 1-11.
a plurality of the drive circuits;
a plurality of power auxiliary circuits respectively corresponding to the plurality of drive circuits;
with
The plurality of power auxiliary circuits are configured so that the driving switching elements of the plurality of driving circuits are sequentially switched so that the power supplied to the sound wave source does not decrease in the operation of generating a series of sound waves from the sound wave source. , supplying power to each of said plurality of drive circuits;
The sound wave generator according to any one of claims 1-12.
a plurality of the drive circuits;
a plurality of power auxiliary circuits respectively corresponding to the plurality of drive circuits;
with
Each of the plurality of power auxiliary circuits has a corresponding one of the plurality of drive circuits in operation to generate a series of sound waves from the sound wave source by sequentially switching the driving switching elements of the plurality of drive circuits. supplying power to the drive circuit during an OFF period of the drive switching element of the corresponding drive circuit;
The sound wave generator according to claim 5.
The power auxiliary circuit is
one or more auxiliary capacitors each charged by one or more auxiliary DC power sources;
At least one of the one or more auxiliary capacitors replaces the capacitor of the drive circuit so that the power supplied to the sound wave source is not reduced in the operation of generating a series of sound waves from the sound wave source by switching the driving switching element. a switching circuit electrically connecting one to the sound wave source;
having
The sound wave generator according to claim 1.
The switching frequency of the driving switching element is 20 kHz or higher.
The sound wave generator according to any one of claims 1-15.
A control circuit that controls the drive circuit and the power auxiliary circuit,
The control circuit powers the drive circuit such that the power supplied to the sound wave source does not decrease while controlling the switching of the driving switching elements of the drive circuit to cause the sound wave source to generate a series of sound waves. controlling the power auxiliary circuit to provide
The sound wave generator according to any one of claims 1-16.